This invention relates generally to laser systems and particularly to a laser system having a frequency doubler device for producing a pair of singularly polarized output beams having identical pulse widths and energies.
In particular radar applications involving laser apparatus, it is desirable that a pair of output light beams be generated from a laser system wherein both of the beams exhibit homogeneous characteristics. That is, the beams are homogeneous with respect to identical energies and pulse widths. In a given application, the generation of a pair of orthogonally polarized homogenized beams within the infrared region may be efficiently utilized in air-to-ground radar applications as target designators and thereby afford the coverage of a larger ground area with a reduction in the time spent over the target. Other radar applications requiring operation within an ocean environment for detection and observation of underwater targets requires the generation of light energy within the green spectrum. Assuming the initial generation of laser light energy within the infrared spectrum such as by the utilization of a neodymium doped yttrium aluminum garnet (YAG) laser device, the output light energy will have to be doubled to produce a green output. Doubler crystals of the type generally well known in the art are sensitive to phase and energy mismatches of light beams selected for doubling. Laser systems have been developed for the generation of laser light energy in a pair of orthogonally polarized rays by Q-switching techniques applied in conjunction with a birefringent crystal. One example of such a laser system is taught in U.S. Pat. No. 3,740,663 to Andringa. Such systems, however, do not anticipate the generation of homogenized light beams and, more particularly, do not exploit the use of such homogenized light beams in conjunction with the critical demands of a frequency doubler crystal for radar applications.